References need not be capable of physical combination in order to show obviousness.In re Etter, 756 F.2d 852, 859 (Fed. Cir. 1985) (in banc); see also, In re Nievelt, 482 F.2d 965, 968 (CCPA 1976) (“Combining the teachings of references does not involve an ability to combine their specific structures”);In re Andersen, 391 F.2d 953, 958 (CCPA 1968) (“There is a distinction between trying to physically combine the two separate apparatus disclosed in two prior art references on the one hand, and on the other hand trying to learn enough from the disclosures of the tw references to render obvious the claims in suit. . . . Claims may be obvious in view of a combination of references, even if the features of one reference cannot be substituted physically into the structure of the other reference.”).